Interpreting MAIA Microperimetry Using Age- and Retinal Loci-Specific Reference Thresholds

Comparison of Microperimetry and Static Perimetry for Evaluating Macular Function and Progression in Retinitis Pigmentosa

Purpose

To compare the usefulness of microperimetry and static automated perimetry in patients with retinitis pigmentosa (RP), using macular anatomical metrics as a reference.

Design

Prospective observational study.

Participants

Forty-eight eyes of 48 patients with RP in Kyushu University Hospital who underwent microperimetry-3 (MP-3) and Humphrey Field Analyzer (HFA) 10-2 testing ≥3 times during ≥2 years were included.

Methods

Macular anatomy (ellipsoid zone [EZ] length) was assessed by OCT, and macular function was assessed by MP-3 (mean retinal sensitivity at radii 2°, 4°, and 8°) and HFA10-2 program (mean retinal sensitivity at radii 2°, 4°, and 8°). Correlations between functional and anatomical parameters were analyzed cross sectionally at baseline and longitudinally by comparing the rate of progression.

Main Outcome Measures

Correlation coefficients between anatomical and functional metrics.

Results

The mean age at baseline was 50.1 ± 12.3 years, and the mean follow-up period was 2.8 ± 0.7 years. At baseline, EZ length was significantly correlated with MP-3 mean retinal sensitivity at radii 2°, 4°, and 8° (Spearman's ρ = 0.65, 0.84, 0.89; all P < 0.005) and HFA10-2 mean retinal sensitivity at radii 2°, 4°, and 8° (Spearman's ρ = 0.61, 0.73, 0.78; all P < 0.005). Longitudinal analysis showed that the slope of EZ length (-88.92 μm/year) was significantly correlated with the slope of MP-3 retinal sensitivity at 8° radius (-0.62 decibels [dB]/year; Spearman's ρ = 0.31, P=0.03) and the slope of HFA retinal sensitivity at 8° radius (-0.60 dB/year; Spearman's ρ = 0.43, P < 0.005).

Conclusions

Both MP-3 and HFA values were cross sectionally well-correlated with EZ length in patients with patients; however, these associations became weaker in the longitudinal analysis. This highlights the need for researchers to explore additional or more sensitive parameters to better monitor RP progression.

Financial Disclosures

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Evaluation of macular integrity, after retinal detachment surgery, using MAIA microperimetry

BACKGROUND AND OBJECTIVE

To describe visual function, macular integrity, and fixation stability using MAIA microperimetry (macular integrity assessment) after retinal detachment surgery. Evaluate if there are statistically significant differences between surgical approaches.

MATERIALS AND METHODS

A prospective, comparative, interventional study was conducted, recruiting a total of 21 patients with rhegmatogenous retinal detachment and macula-off. Eleven patients underwent surgery using pars plana vitrectomy (PPV), and 10 patients underwent scleral buckle surgery. Clinical examinations and optical coherence tomography (OCT) were performed post-surgery. MAIA microperimetry was conducted at 6 months.

RESULTS

Best-corrected visual acuity (BCVA) and the number of letters read improved over time in the operated eye but did not reach the level of the control eye (p = 0.001). No significant differences were found between the two surgical approaches in BCVA (p = 0.230) or the number of letters read (p = 0.608). Macular integrity in the operated eye did not match that of the control eye in both procedures (p = 0.05). No differences were detected between the two surgeries, either in macular integrity (p = 0.512) or fixation stability (p = 0.835).

CONCLUSIONS

Following retinal detachment surgery, a decrease in BCVA and the number of letters read occurs, which does not reach the level of the control eye. No significant differences were observed between the two surgical approaches. Macular integrity in the operated eye does not match that of the control eye.

The Natural History of Retinal Sensitivity Loss in Diabetic Macular Ischemia over One Year Evaluated by Microperimetry

Background/Objectives: This one-year prospective observational study, conducted at two centers, aimed to report the natural history of retinal sensitivity (RS) loss in diabetic macular ischemia (DMI). Methods: Patients with stable-treated proliferative diabetic retinopathy (PDR) were recruited if there was evidence of DMI on optical coherence tomography angiography, defined as a foveal avascular zone ≥ 0.5 mm2 or parafoveal capillary dropout ≥ 1 quadrant. The minimal visual acuity required for performing microperimetry (MP) was ≥54 Early Treatment Diabetic Retinopathy Study letters (Snellen equivalent 20/80). The overall RS (oRS) and pointwise sensitivity (PWS) within the 3 × 3 mm macula were assessed at baseline and twelve months. A value <25 decibels (dB) was defined as impaired RS, and a decrease of 2 and 7 dB was regarded as mild and severe loss, respectively. Results: A total of 88 patients (97 eyes) were included. No statistically significant MP changes were detected at one year. However, 10% of the cohort lost oRS ≥ 2 dB, and 73% lost ≥2 dB PWS in ≥5 loci, whereas 1% lost oRS ≥ 7 dB, and 4% lost ≥7 dB PWS in ≥5 loci. The foveola and temporal parafovea were the most vulnerable to severe RS loss. Compared to their counterpart, eyes with baseline oRS ≥ 25 dB had significantly more RS loss in the macula and superior parafovea (55% versus 32% and 53% versus 28%, both p = 0.01). Conclusions: Rather than oRS loss, ≥2 dB loss in PWS in ≥5 loci is a more feasible outcome measure for clinical trials in DMI.

Topographic Correlation of Microperimetry With Structural Characteristics in Diabetic Macular Ischemia

PURPOSE

This study aimed to determine the threshold for defining abnormal retinal sensitivity (RS) that correlates with structural changes in diabetic macular ischemia (DMI) patients with stable treated proliferative diabetic retinopathy (PDR).

DESIGN

Prospective cross-sectional study.

METHODS

In a single center, we recruited 85 eyes (67 patients) with stable treated PDR with best-corrected visual acuity (BCVA) ≥54 Early Treatment Diabetic Retinopathy Study (ETDRS) letters (Snellen equivalent 20/80) and optical coherence tomography angiography evidence of DMI. The function-function and function-structure correlation were assessed. Two preselected thresholds in overall RS (oRS), 25 decibels (dB) and age-matched normative data (AMND), were tested on their ability to reflect abnormal anatomy in DMI. Finally, a multivariable regression model was established to depict the relationship between the oRS and various parameters.

RESULTS

The oRS showed only a modest correlation with BCVA and low-luminance visual acuity (LLVA). The whole-image deep vessel density (wiDVD) was the most reliable vascular metric correlated with RS. For every 1% decline in the wiDVD, the oRS decreased by 0.37 dB (P < .001) after multivariable adjustment. Furthermore, both a reduction of oRS to <25 dB or below AMND could differentiate eyes with FAZ ≥0.5 mm2, whole image superficial vessel density (wiSVD) <37.7%, wiDVD <41.9%, and the presence of disorganization of the retinal inner layers (DRIL) from their counterparts.

CONCLUSIONS

The absolute value of 25 dB in oRS is worth considering as a trial endpoint, because it does not require complex calculation and closely reflects the structural abnormalities in DMI.

Baseline Microperimetry and OCT in the RUSH2A Study: Structure-Function Association and Correlation With Disease Severity

PURPOSE

To investigate baseline mesopic microperimetry (MP) and spectral domain optical coherence tomography (OCT) in the Rate of Progression in USH2A-related Retinal Degeneration (RUSH2A) study.

DESIGN

Natural history study METHODS: Setting: 16 clinical sites in Europe and North AmericaStudy Population: Participants with Usher syndrome type 2 (USH2) (N = 80) or autosomal recessive nonsyndromic RP (ARRP) (N = 47) associated with biallelic disease-causing sequence variants in USH2AObservation Procedures: General linear models were used to assess characteristics including disease duration, MP mean sensitivity and OCT intact ellipsoid zone (EZ) area. The associations between mean sensitivity and EZ area with other measures, including best corrected visual acuity (BCVA) and central subfield thickness (CST) within the central 1 mm, were assessed using Spearman correlation coefficients.

MAIN OUTCOME MEASURES

Mean sensitivity on MP; EZ area and CST on OCT.

RESULTS

All participants (N = 127) had OCT, while MP was obtained at selected sites (N = 93). Participants with Usher syndrome type 2 (USH2, N = 80) and nonsyndromic autosomal recessive Retinitis Pigmentosa (ARRP, N = 47) had the following similar measurements: EZ area (median (interquartile range [IQR]): 1.4 (0.4, 3.1) mm2 vs 2.3 (0.7, 5.7) mm2) and CST (median (IQR): 247 (223, 280) µm vs 261 (246, 288), and mean sensitivity (median (IQR): 3.5 (2.1, 8.4) dB vs 5.1 (2.9, 9.0) dB). Longer disease duration was associated with smaller EZ area (P < 0.001) and lower mean sensitivity (P = 0.01). Better BCVA, larger EZ area, and larger CST were correlated with greater mean sensitivity (r > 0.3 and P < 0.01). Better BCVA and larger CST were associated with larger EZ area (r > 0.6 and P < 0.001).

CONCLUSIONS

Longer disease duration correlated with more severe retinal structure and function abnormalities, and there were associations between MP and OCT metrics. Monitoring changes in retinal structure-function relationships during disease progression will provide important insights into disease mechanism in USH2A-related retinal degeneration.

Localised relative scotoma in cuticular drusen

PURPOSE

To investigate retinal sensitivity changes in eyes with pure cuticular drusen.

METHODS

Multimodal imaging and microperimetry (37-loci grid) data were examined retrospectively to evaluate functional changes in eyes with pure cuticular drusen. Mean sensitivity in the cuticular drusen cohort was compared to age-matched normals. An age- and loci-specific normative reference was created to analyse localised sensitivity deviation.

RESULTS

The mean number loci with relative scotoma in the cuticular drusen cohort (n = 27, mean [SD] age: 48.5 [12.4] years) referenced to normal eyes (n = 80, 53.5 [14.6] years) was 5.5 (95% confidence interval 3.0 to 8.1). However, mean sensitivity was not statistically different to the age-matched normal cohort (95% CI, - 2.3 to + 3.4 dB). The 37-loci grid was stratified into three rings of the approximately same number of loci, and the percentage of cuticular drusen eyes with pointwise deviation was significantly lower in the inner compared to the middle ring (12.3 [5.3]% vs. 17.3 [5.1]%, p < 0.05).

CONCLUSIONS

Eyes with cuticular drusen demonstrated relative scotoma, but mean sensitivity was not affected. Pointwise sensitivity provides a more robust measure of retinal sensitivity than mean sensitivity in cuticular drusen and should be assessed both in the clinic and in future clinical trials.

Macular sensitivity assessment and fixation analysis using microperimetry in children with retinopathy of prematurity

BACKGROUND/AIMS

To investigate retinal sensitivity and fixation stability using microperimetry in children with retinopathy of prematurity (ROP).

METHODS

Observational case series. Totally 51 preterm children who had been followed for ROP were examined in three groups (n=17 in each group). The groups were defined as children without ROP (group 1), children with spontaneously resolved ROP (group 2) and children who had laser treatment for ROP (group 3). All subjects underwent a detailed ophthalmic examination. Macular Analyzer Integrity Assessment Microperimetry was used to analyse macular light sensitivity and fixation stability. The results were compared between groups. The measurements were also analysed according to age, gender, birth weight and gestational age.

RESULTS

The mean age was 10.84±0.97 years, and 27 children were female. Mean average threshold (AT) for macular sensitivity was 25.5±2.1 decibel in group 1, 26.8±3.8 decibel in group 2 and 26.3±3.0 decibel in group 3. These differences were not statistically significant between the groups (p=0.067), but AT was abnormal in 29% of the whole study population. Outputs about fixation stability were similar between the three groups but fixation was unstable in 27% of the subjects. Mean AT was better in children ≥11 years old compared with the younger ones (p=0.022).

CONCLUSION

Preterm children may have some abnormalities in macular light sensitivity and fixation stability. These abnormalities may be more prominent in children less than 11 years old. ROP itself or the laser treatment seems not to affect macular light sensitivity and fixation stability.

Microperimetry Hill of Vision and Volumetric Measures of Retinal Sensitivity

Purpose

Mean retinal sensitivity is the main output measure used in microperimetry. It is, however, of limited use in patients with poor vision because averaging is weighted toward zero in those with significant scotomas creating an artificial floor effect. In contrast, volumetric measures avoid these issues and are displayed graphically as a hill of vision.

Methods

An open-source program was created to manipulate raw sensitivity threshold data files obtained from MAIA microperimetry. Thin plate spline interpolated heat maps and three-dimensional hill of vision plots with an associated volume were generated. Retrospective analyses of microperimetry volumes were undertaken in patients with a range of retinal diseases to assess the qualitative benefits of three-dimensional visualization and volumetric measures. Simulated pathology was applied to radial grid patterns to investigate the performance of volumetric sensitivity in nonuniform grids.

Results

Volumetric analyses from microperimetry in RPGR-related retinitis pigmentosa, choroideremia, Stargardt disease, and age-related macular degeneration were analyzed. In simulated nonuniform testing grids, volumetric sensitivity was able to detect differences in retinal sensitivity where mean sensitivity could not.

Conclusions

Volumetric measures do not suffer from averaging issues and demonstrate superior performance in nonuniform testing grids. Additionally, volume measures enable detection of localized retinal sensitivity changes that might otherwise be undetectable in a mean change.

Translational Relevance

As microperimetry has become an outcome measure in several gene-therapy clinical trials, three-dimensional visualization and volumetric sensitivity enables a complementary analysis of baseline disease characteristics and subsequent response to treatment, both as a signal of safety and efficacy.

Low Luminance Visual Acuity and Low Luminance Deficit in Choroideremia and RPGR-Associated Retinitis Pigmentosa

Introduction

Choroideremia and RPGR-associated retinitis pigmentosa (RP) are two distinct inherited rod-cone degenerations, where good visual acuity (VA) is maintained until late disease stages, limiting its usefulness as a disease marker. Low luminance VA and low luminance deficit (standard VA minus low luminance VA) may be more sensitive visual function measures.

Methods

Standard VA was obtained using Early Treatment Diabetic Retinopathy Study letter charts (Precision Vision, Bloomington, IL, USA). Low luminance VA was assessed using a 2.0-log unit neutral density filter, with the same chart setup, without formal dark adaptation. Mean central retinal sensitivity was assessed using MAIA microperimetry (Centervue SpA, Padova, Italy). Optical coherence tomography imaging was attained with Heidelberg Eye Explorer software (Heidelberg Engineering, Heidelberg, Germany).

Results

Twenty-four male participants with confirmed pathogenic RPGR mutations, 44 male participants with confirmed pathogenic CHM mutations, and 62 age-matched controls underwent clinical assessment prior to clinical trial recruitment. Low luminance VA was significantly reduced in both disease groups compared to controls. The low luminance deficit correlated with microperimetry retinal sensitivity and ellipsoid zone width. Eleven participants with moderate VA had poor low luminance VA (subsequently a large low luminance deficit), no detectable microperimetry sensitivity, and severely constricted ellipsoid zone widths.

Conclusions

Low luminance VA and subsequently low luminance deficit are useful markers of central macular visual function in both choroideremia and RPGR-associated RP, when standard VA is preserved.

Translational Relevance

Low luminance visual acuity and low luminance deficit are useful vision measures in two distinct rod-cone degenerations and may be useful in other retinal degenerations.

Fundus-controlled perimetry (microperimetry): Application as outcome measure in clinical trials

Fundus-controlled perimetry (FCP, also called 'microperimetry') allows for spatially-resolved mapping of visual sensitivity and measurement of fixation stability, both in clinical practice as well as research. The accurate spatial characterization of visual function enabled by FCP can provide insightful information about disease severity and progression not reflected by best-corrected visual acuity in a large range of disorders. This is especially important for monitoring of retinal diseases that initially spare the central retina in earlier disease stages. Improved intra- and inter-session retest-variability through fundus-tracking and precise point-wise follow-up examinations even in patients with unstable fixation represent key advantages of these technique. The design of disease-specific test patterns and protocols reduces the burden of extensive and time-consuming FCP testing, permitting a more meaningful and focused application. Recent developments also allow for photoreceptor-specific testing through implementation of dark-adapted chromatic and photopic testing. A detailed understanding of the variety of available devices and test settings is a key prerequisite for the design and optimization of FCP protocols in future natural history studies and clinical trials. Accordingly, this review describes the theoretical and technical background of FCP, its prior application in clinical and research settings, data that qualify the application of FCP as an outcome measure in clinical trials as well as ongoing and future developments.